Culture corner
The Eastern Province Orchid Society
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The Eastern Province Orchid Society
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Resupination Pronounced re-soup-i-nation, it has nothing to do with getting a second serving of soup! Resupination is the process by which the flowers of many orchids, as they open, twist so that the lips are orientated below the other floral segments. All of the commonly known genera (Cymbidium, Dendrobium, Phalaenopsis, etc) have resupinate flowers. Twisting is due to rotation of both the ovary and pedicel. One of the many interesting features of resupination is that the flowers only undergo it if it is necessary to orientate themselves so that their lips are lowermost. Thus the flowers on the ascending part of an arching inflorescence undergo resupination, while those on the descending part do not. Another curious feature is that, as a general rule, the direction of resupination alternates from flower to flower up the inflorescence. For example, if the first flower twists in a clockwise direction, then the second one twists in an anti-clockwise direction and so on! Resupination begins to occur as the buds open and is essentially complete by the time the floral segments are fully expanded. Why are most orchid flowers resupinate? The main theory is that resupination orientates the lip to provide the orchid’s pollinator with a convenient landing pad. Most resupinate orchid flowers twist through 180 degrees as they open but the flowers of Angraecum superbum rotate through 360 degrees, so that they eventually reach the same orientation as if they were non-resupinate! Orchids with non-resupinate flowers include Osmoglossum pulchellum and some Satyrium species. From an aesthetic viewpoint, resupination is important to orchid growers. Nothing looks more ridiculous than an arching cymbidium spike that has been staked upright after the flowers have opened. All the flowers face upwards, with their lips uppermost. By all means, stake such an inflorescence upright for transport but on arrival release the ties so that the flowers are displayed in their customary manner. By kind permission of the Orchid Societies Council of Victoria Inc (Source: Resupination by J. & M. Arditti, R. Ernst and L.P. Lyman, Proc. 12th World Orchid Conference, Japan, 1987.) Feeding and Spraying Program: by Des Gillespie Download a useful spreadsheet copy of the feeding and spraying program. Orchid named after Wendy Davis Nollie Cilliers of Plantae in Pretoria bought a beautiful red cattleya from Leon and Wendy Davies, which was an unregistered grex (Sc Tangerine Jewel X Bl Burdekin Storm). It received an HCC from the SAOC earlier this year and Nollie decided to name it after Wendy for being such a wonderful person. The Royal Horticultural Society has registered it as Rhyncosophrocattleya Wendy Davies ‘Radiant Ruby’.
Drying out time for Cymbidiums: by Rina Rentzke I am always a little perplexed when I read the latest orchid book only to find that here is very little by way of new information. It would seem as though Cymbidium culture has not advanced for the last 50 years with the information supplied sometimes being so outdated that it could be detrimental to the health of your plant! I often read about giving Cymbidiums a “drying out time” - this statement has most probably killed more Cymbidiums than any other problem. So many growers take this to mean completely dry, which sets the plant back a little; eventually destroying the root system. Very often a book will recommend fertilizing once a month, whereas the accepted method by many of today’s top growers, commercial and hobbyist alike, is to fertilize at a far lower strength every time the plants are watered. These growers also have a programme which is designed to get optimum growth. After all these guys have plants to sell and shows to win! I don’t think that I have ever seen one of these programmes in any book that I have read. It is for this reason that we have produced a Cymbidium culture programme (although all genera in my collection seem to do well on it) which is available to members. Just about every book that I have read is quite adamant that one should never stand Cymbidiums in water as this will supposedly rot the roots. I sometimes wonder where they got this information from and whether they have actually tried this method of growing. I have been standing my plants in water for about six years now and have yet to experience root rot! Instead my plants have flourished and grown like never before. Can this be another old wives tale? During my trip to Australia in 2006 I told Terry Polton, a well known Cymbidium grower and hybridiser, about my method and he responded that he had been growing his plants in water for the past twenty years! He then very proudly showed me his very latest pot design which actually has a reservoir included in the bottom of the pot. I recently found an American website for Ray’s Orchids and they sell these pots. They are about 40 or 50mm deeper than our standard pots and instead of holes in the bottom they have holes about 25mm up the side of the pot. They call this semi-hydroponics. So if your Cymbidiums are not doing well you might want to try this method of growing by starting off with one plant but I am sure that before long you will be growing the rest of your plants this way as well. I find that the best source of information does not come from books but from the journals Australian Orchid Review and Orchids Australia. These articles are often written by experienced growers who really know their orchids and are prepared to pass on their knowledge gained over many years. I have been granted permission from the Australian Orchid Review to copy these articles which will be sold at a nominal cost to our members at the shop and our monthly meetings. It has taken a lot of work to find the best articles and I therefore hope that members will make use of this service. New names for old inter-generics: RHS changes the rules: by Dan O'Connor I must keep reminding myself that my interest in orchids is horticultural and nothing else, but it’s hard when one has an interest in hybrids as well as species. Usually when generic names are changed, the previous generic name is retained for the purpose of hybrid registration. Recently however, the RHS published new generic names for all the Cattleya hybrids affected by the creation of a new genus and the movement of species to other genera. Some years back, a building block species in the cattleya alliance, Brassovola digbyana was moved to a new genus namely Rhyncolaelia. All very well we said, this alignment happens as DNA tests reveal the similarities or otherwise between genera. The classification process is in a state of flux. The change of name to Rhyncolaelia did not affect the number of inter-generic hybrids that had been registered and Brassolaeliocattleya (Blc) still remained as the inter-generic description of these hybrids. Blc.Norman’s Bay, Blc.Pamela Hetherington and Blc.Triumphal Coronation are some of the well known hybrids that appear on our plant table from time to time. In 2003, four Cattleya species and a natural hybrid from the subgenus ‘circumvolva’ were moved to a brand new genus named Guarianthe. The name Guarianthe is based on the Costa Rican common name Guaria used to describe orchids. Cattleya skinneri is the national flower of Costa Rica and its common name there is Guaria morada which means Purple Orchid. The affected species and natural hybrid were: C. skinneri, C. aurantiaca, C. bowringiana, C. patinii and C. guatemalensis. The creation of a new genus was justified because these plants are very different from the labiate-type cattleya; they have several thin-jointed pseudobulbs with a bulbous base, and two (sometimes three) elliptic/oblong leaves at the apex of the pseudobulb. The inflorescence and flower structure are also different. Prior to this, a very diverse group of orchids, known as the Brazilian Laelias were moved to an existing but smaller genus known as Sophronitis. This caused a stir in the botanical world because the Laelias are very different in morphology, size etc. They are grouped in four subgenera or sections each as different from the other as they are different from the Sophronitis genus. All they have in common is eight pollinia. Was this the criteria used by the taxonomists we asked? It seems it was! More than forty Brazilian Laelia species were moved to the genus Sophronitis. Well, what has this got to do with hybrids? A lot, the new inter-generic descriptions for Cattleya hybrids involving Brassovola, Laelia and four new Cattleya species have changed. I would guess as many as thirty thousand plants are affected by the new names. Here are a few: Lc .Molly Tyler an old favourite is now known as Guarisophleya Molly Tyler, Blc. Triumphal Coronation is now Rhynchosophrocattleya Triumphal Coronation and Potinara Free Spirit is Thwaitesara Free Spirit. I wait with interest to see how the abbreviations are applied. Will Blc. Become Rsc? To find the new name of your inter-generic hybrid, visit the RHS web site and go to Plant Registration. Select Grex name search. Leave GENUS blank and put plant name in GREX box. Ask for exact match and click on search. Cymbidium culture notes: by Des Gillespie Cymbidiums are relatively easy to grow and flower successfully. Here are some simple tips that may help you: 1. Water regularly; never let your plants dry out. Water the roots only during cold weather. 2. Fertilize your plants with every watering, at quarter to half strength, i.e. 400 - 600 micro-siemens, if you are using rain water. 3. Ensure that the pH of the water is 5.5 to 6.5 after adding the nutrient. ( If using rain water the addition of fertilizer would bring it to within this range.) 4. A good feed of Nitrosol once a month during the summer months (December to February) will give the plants a good boost. 5. Cymbidiums are prone to fungus attack. Adopt a regular programme to keep fungus at bay. Remember: prevention is better than cure. 6. The addition of Lime to your pots every 4 months will keep the media "sweet" and also make it last longer. 7. Watch out for insect damage and spray as soon as possible, remember not to spray systemic fungicides or insecticides while the flower buds are forming as this may cripple them. 8. Start staking your flower spikes as early as possible in order to train them upright and if you are growing under shade-cloth, provide some waterproof protection so that the flowers don't get marked. I wish you all a successful Cymbidium year. Method for treating coconut husk chips before use: by Des Gillespie The untreated block swells to about 50 litres when hydrated, so use a container that will hold this volume. Fill the container with 25 to 30 litres of water. Rainwater is preferable but not essential at this stage. Untreated municipal tap water can be used regardless of the Ph or EC. Before placing the block into the water, mix in :
Place the block into the water and allow to soak for at least 2 days. Give it a stir every now and then and top up the water if necessary. When the material is ready, spread it over a 6mm sieve and using a jet of water from your hosepipe, wash out the fines. The latest consignment of coconut husk does not have much in the way of fines as the suppliers are doing most of the washing. I still prefer to wash it though. On completion of the washing process allow the medium to drain. The final flush is done using your nutrient (fertiliser) water. Due to its fibrous nature, coconut husk very quickly takes on the Ph and EC of the nutrient. For the first few waterings after potting, give the pots a good soak just to make sure that all the fines have been removed. An initial pre-wash can also be done to remove much of the tannin from the medium. Watering cymbidiums: by Des Gillespie A lot has been said over the years about the over-watering of Cymbidiums. So much so that I find it difficult convincing growers that Cymbidiums should never be allowed to dry out. I would go so far as to say that you cannot over-water a Cymbidium! They love water! If the weather is cold, then don’t wet the foliage but do not withhold water from the root systems. If you are watering your Cymbidiums because they are too dry, you need to change your way of thinking and you should rather be watering because they need a change of spent nutrient within the pot. I have found that it is best to fertilise them at half strength (600-800 micro-siemens) with every watering. My fertilising program is based on the Bryant’s formulae and is a 6 week programme as follows :
Feed at 600-800 micro-siemens (half strength0 from March to November. Increase mix 1 and 2 to 1000 micro-siemens from December to March. A full 52 week program will be available at the September meeting and thereafter at the Society’s shop. It will be a week by week guide to growing cymbidiums and will include spraying programmes for fungi and bugs. If you have any questions regarding this, contact me and I will try to assist. Markings on the leaves of cymbidiums: by Rina Rentzke A friend recently asked me to visit and have a look at her cymbidiums as they had developed markings on the leaves. The first thought that enters one’s mind of course, is VIRUS!!!
But just to confuse orchid growers, not all markings are virus symptoms. It could be fungal, bacterial or a nutritional problem! None of the other genera in the collection showed any signs of the infection, which made me suspect that this might be a fungal or bacterial infection peculiar to cymbidiums. This jogged my memory as I had seen something similar in Australia at Wain’s Orchid Nursery. David Wain told me that he has sent samples of the infected plants to a lab and the report back was negative for virus. He treated the plants with a systemic fungicide and the new growths showed no signs of the infection. We are going to treat the infected cymbidiums with Benlate and Previcur, which are both available at The Shop. (See the back page for prices). If you see any markings on the leaves of your plants, remove them from your orchid house as some fungal and bacterial infections are extremely contagious. Remember : PREVENTION IS BETTER THAN CURE! Culture guides:
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Last modified: June 24, 2008
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